High-pressure hydraulic pump



March 16, 1954 R. LUCIEN ET AL 2,672,095

HIGH-PRESSURE HYDRAULIC PUMP Filed Dec. 20, 1949 Patented Mar. 16, 1954 HIGH-PRESSURE HYDRAULIC PUMP Ren Lucien and Eugen Ludwig Miiller, Paris,

France, assignors to Societe dlnventions Aeronautiques et Mecaniques S. I. A. M., Geneva, Switzerland, a corporation of- Switzerland Application December 20, 1949, Serial No. 134,056

' Claims priority, application France August 6, 1949 3 Claims.

Our invention relates to hydraulic pumps of the so-called drum or barrel type, i. e. in which pistons arranged about a common axis are adapted to be actuated, in their respective cylinders, by a wabble or swash plate which is inclined with respect to said axis and is actuated by .a rotor.

Such pumps, which are in general intended for supplying a high-pressure liquid for actuating various apparatus, are frequently used in aircraft because of their regular output andtheir light weight and small bulk.

Our invention provides an improved pump of the foregoing'type, which has a number of constructional arrangements whereby its weight and its bulk are fundamentally smaller than those of the known pumps of the same type.

A first feature of the invention consists in substituting for the usual arrangement, i. e; the axially staged arrangement, of said swash plate, its drivingrotorand the race of said rotor, an interfitting arrangement of these members in such a manner that said plate is located substantially in the same transverse plane as the race, instead of being axially staggered with respect thereto, thereby enabling simultaneously a considerable shortening of the pump to be effected and all the stresses set up by the pistons to be transmitted to the pump body by said race.

A second feature of the invention consists in effecting the return of the pistons during their suction stroke by means of a second swash plate,

the pistons thus operating between two swash plates. This method of drive makes it possible to substitute for the usual separate springs for retracting the pistons, a common spring which is housed coaxially in the'barrel and to decrease still further not only the lengthbut also the diameter of the pump; V

A third feature of the invention, which is applicable to pumps provided with hollow pistons and inlet valves mounted .on the pistons themselves, consists in fixing the opening abutment of each of the valves by means of resilient arms completely housed inside grooves which are cut in the bearing surfaces of the pistons so that said arms do not project above the sliding surface of the piston. This method .of fixing the abutments enables the length of the pistons, and consequently that of the pump, to be decreased without decreasing the length of the useful bearing surface of the pistons.

A fourth feature of the invention consists in mounting, inside the rotor itself, a small auxiliary centrifugal pump of very small size, which sucks, and forces into the casing ofthe main Fig. 1 is a view in vertical section along the axis of the pump;

Fig. 2 is a view in transverse section of a piston along the plane projected on II-II in Fig. 1;

Fig. 3 shows the opening abutment of an inlet valve, with its resilient arms.

I denotes the pump body; 2 and 3 respectively denote the inlet and the outlet for the liquid; 4 is the cover which closes the pump body on the driving side.

A nut 5 secures the barrel 6 inside the body of the pump. In the barrel 6 are bored a number of cylinders, within which are respectively adapted to move axially perforated pistons l which rest by means of half-balls 8 on a swash plate which in this case is constructed in the shape of a ring 9 mounted on balls [9 obliquely with respect to the axis X--X of the pump body, said plate receiving its oscillatory movement from a rotor II which is driven by the splined driving shaft Ha and rotates on balls l2 inside a race I3 against which the cover 4 is adapted to bear. 1

It can be seen that, according to one of th characteristic arrangements of the invention,

the ring 9 is located inside the rotor II which is in turn located inside the race [3, so that the ring 9 is located substantially in the same transverse plane as the race l3, said plane, Z--Z, being approximately defined by the centre of the balls I2 and the centre of the ring 9.

This interfitting arrangement provides a very substantial reduction in the size of the pum in the axial direction, as compared with the known constructions in which the corresponding members are superposed on one another along the axis.

The return of the pistons 1 is effected by the action of a swash plate It provided with peripheral openings I5 by means of which it en- 3 gages said pistons, this retracting plate bein adapted to bear by means of a common flat surface against the shoulders 13 respectively secured to said pistons. This bearing is ensured by a powerful spring H, the action of which is exerted either directly, or by means oi the member I8 and the ball [9, on the swash plate M in such a manner that said plate It describes approximately circular movements on the shoulders I6 with practically negligible friction.

It will be observed that this arrangement of the spring H, which is housed coaXially in the barrel and is common to all the pistons, enables the transverse dimension of the pump to be reduced and that the provision of this collective spring, as compared with the separate springs usually used, enables the axial. dimension. of the pump to be reduced.

During the down-stroke of each piston 1, the corresponding inlet valve 29 is forced upwards by the liquid sucked intothe cylinder, until it encounters its abutment 2!. According to them-- vention, said abutment is provided with resilient arms 22 which are terminated by hooks 23. The arms 22 are respectively housed in longitudinal grooves- 24 which are providedin the pistons I and inside. which said arms are pressed with a high pressure, while the books 23 penetrate into transverse slots 25 likewise provided in the pistons T. with hooks, which are completely housed: in the actual. body of the pistons. and act as means for anchoring the abutment, enables the length. of. the pistons and consequently that of the pump to be reduced substantially.

The delivery of the liquid is effected, according to a method known per se, by the action of spring-actuated valves 26 through ducts 2'! provided inthe barrel 6.

The fluid-tightness of the. pump at the point where the rotor H passes through the, cover 4 is obtained by means of rotary joints 28-29,-3D

The liquid which infiltrates between. the joints. 28 and 29 is subjected to the action of centrifugal force which projects it towards the opening of the pump. through. the duct 3! and the valve 312 which. is in turn slightly opened by the action of centrifugal force. When the pump. is inoperative, the. spring 53 which, bears against the pin34 presses the valve 32 against its seat.

We. claim:

1.. A hydraulic pump of the barrel type comprising in combination: a pump body and a fixed cylindrical member inside the pump body defining therewith two chambers separated by the cylindrical member and having respectively an inlet or suction port and an outlet or discharge port; a plurality of cylindrical bores in the cylindrical member defining Working cylinders each.

This arrangement of the-resilient arms Number Name Date 1,541,166 Mowers June S 1925 1,898,664; Koschka June. 2,193]. 2,365,309. Talbot: Bot 19, 1943 r FDRE'IGN PATENTS I Number Country Date 311,938 Great Britain 1929' 487,176 Germany 1929' 556,384 Germany 1932 having a piston slidable therein, the bores being distributed equidistantly about, and having their axes parallel to, the axis of the cylindrical member; a dished drive rotor having a drive shaft extending therefrom out of: the pump body in alinement with said axis; means defining a race inside the dished rotor in a plane inclined to said axis; a first swash plate positioned to ride on the race and engage the pistons endwise to urge them intotheir respective cylinders; the pistonshaving shoulders adjacent the ends thereof engaged by the first swash plate and facing from said ends; a second swash plate having apertures adjacent. the periphery thereof embracing the pistons; a helical spring positioned in a central recess inside the cylindrical member and bearing on second swash plate to cause engagement thereof with the piston shoulders, the individual coils of the spring being spaced from each other to permit a total contraction of the spring substantially equal to. the stroke of the pistons; the pistons. being hollow and communicating at their ends with the two chambers", and a non-return: valve. mounted on each piston at the end thereof in communication with the chamber'having a discharge pert.v

2. In a pump as claimed in claim 1 abutments limiting the opening of said valves, resilient. arms connecting said. abutments to: their respective pistons, books at. the free ends of said resilient arms and grooves provided. in the sliding surface of said pistons and serving tOl house said resilient arms 8. In a pumpas claimed inclaimil, amauxiliary centrifugal pump for the recovery of. leakages from the rotary joint of the. rotor drive. shaft through the body. oiithemaimpnmp, said auxiliary pump comprising a duct: communicating; on the one hand, with said joints, and. on. the. other hand, with the inside. of the pump body, a valve housed in said duchand subiected to-the centriiugal torce, anda spring tor said valve biassing said valve in opposition to centrifugal force.

RENELEICIENW EUGEN'LUUWIG References Cited in the. tile. 0t this patent UNITED STATES PATENTS 

